AR and RUNX2 targets in prostate cancer. Fatal prostate cancer (CaP) is typified by androgen independence and metastasis to bone. Are the two processes linked? The former is driven by an aberrant androgen receptor (AR) signaling axis, while the latter is associated with the osteoblast-specific transcription factor RUNX2 in CaP cells. The goal of this project is to identify AR (specific aim #1) and RUNX2 (specific aim #2) target genes in CaP cells using a novel, unbiased genomic experimental approach, which we have recently developed (called ChIP Display, CD). We predict the identification of three groups of genes, those regulated by AR, those regulated by RUNX2 and those regulated by both, possibly in a synergistic manner. The latter group of genes might provide insight into mechanisms that govern androgen resistance of bone metastatic deposits (specific aim #3). In specific aim #4 we intend to experimentally test AR/RUNX2 co-occupancy at target sites coupled with gene expression and molecularly dissect the known AR/RUNX2 interactions in structural and functional terms. Successful completion of these aims will lead to a mechanistic understanding of the CaP phenotypes of androgen independence and predilection to bone. Two main hypotheses will be tested: (i) Androgen independent CaP is driven by aberrant AR or AR/RUNX2 signaling through target genes that control processes such as cell cycle progression, and (ii) bone predilection of prostate cancer cells is driven by RUNX2 or RUNX2/AR target genes that control the expression of bone- specific, osteomimetic genes to consolidate cell growth in bone.